I. Field of the Invention
The invention herein relates to enhancement of type impressions.
II. Background Information
It is desirable in many cases to enhance the type impression on a paper sheet by raising the type impression or giving the appearance of the impression being raised. In some cases the impression is physically raised, as occurs in an embossing process. Such processes, however, are very expensive since they require the formation of a embossing dye, and a new dye must be formed for each different type impression which it is desired to form.
In order to reduce the expense of providing a raised type impression, the process of thermography was developed a number of years ago. In thermography specially developed slow drying inks are used to print a type impression on a sheet using conventional (usually typeset or rubber stamp) printing methods. Thereafter, while the slow drying ink remains wet, thermography powder is spread on the wet ink, heat is applied and the thermography powder is fused with the wet ink. The resulting type impression gives the impression of being raised, since the impression now has a thick coating of the fused thermography powder overlaying the type impression and incorporated at its lower service into the wet ink. Each sheet is then allowed to sit for sufficient time for the coated slow drying ink to dry and the sheet can then be used in a conventional manner.
The thermography process and the slow-drying inks used in the process have been widely described in the literature. Typical examples of such descriptions will be found in Campbell, The Designer's Handbook, 135 (1983); Craig, Production for the Graphic Designer, 91 (1974); and Dennis, et al., Comprehensive Graphic Arts, Unit 119 (1974). Heretofore, however, there was no recognition by the art that an equivalent enhancement of type impressions could be obtained from any other types of inked impressions, and particularly there was no recognition that type impressions from mechanical ribbons could be so enhanced.
Also known is the thermal printing or thermal transfer process, which uses an electrically resistive apparatus to fuse ink to a paper. This process, however, requires complex equipment and specially formulated resistive printing inks, and is not analogous to thermography.
In recent years, many of the sheet products, such as letterheads, brochures and the like, which previously were produced by conventional print techniques and in commercial print shops, have more and more been produced directly by the end users themselves, particularly using personal computers and word processing or desk top publishing software and dot matrix or impact printers. However, there has been no ability for creating the enhanced raised appearance of the impressions from such printers, so that in order to obtain such enhancement the consumers have been forced to forego their use of in-house word processing or desk top printing capabilities and return to the commercial printers for conventional wet ink thermography. It would therefore be of significant advantage for users to have a process which will enable them to enhance type impressions formed by dot matrix and impact printers and similar printing devices, without the necessity of having to have the enhanced printing produced by commercial print shops. It would also be advantageous for such a process to be conducted quickly, easily and inexpensively right in the user's own office or home or even at the user's own desk.